转座子Tn5对柠檬酸细菌的诱变

含自杀性质粒 PJB4JI：：Mu：：Tn5的大肠杆菌1830与四株柠檬酸细菌作接合杂交均能获得Kanr转移接合子。其中一株(c-3-1)的Kayr转移接合子中绝大部分对庆大霉素敏感。鉴别了3000个这样的转移接合子菌落获得了2l株营养缺陷型，其中赖氨酸1株，尿嘧啶1株，精氨酸2株，异亮氨酸2株，组氨酸2株，甲硫氨酸株，苯丙氨酸1株，酪氨酸1株，丝氨酸1株，苏氨酸1株，亮氨酸3株，脯氨酸1株，腺嘌呤3株和乳糖利用1株。用琼脂糖电泳检查部分营养缺陷型突变体DNA均未发现自杀性质粒PJB4JI：：Mu：：Tn5，以32p标记的Tn5 DNA为探针与每个营养缺陷型的染色体作杂交均看到了Tn5 DNA同源序列的存在。由此得出结论，这些营养缺陷型产生于转座子Tn5从自杀性质粒PJB4JI到c-3-1染色体的转座。

Transpon Tn5 mutagenesis in Citrobacter

When E. coli 1830/PJB4JI mating with four Citrobacter strains all were Kanamycin resistant, but a majority of KanrGens transconjugants were obtained from C-3-1. Among 3000 KanrGens 21 were auxotrophs, these are Lys-(1), Ura-(1), Arg-(2), Iso-(2), His-(2), Met-(1), Phe-(1), Tyr-(1), Ser-(1), Thr-(1), Leu-(3), Pro-(1), Ade-(3), Lac-(1), PJB4JI plasmid DNA were detected in parent strain E. coli 1830, but not in auxotrophs strains which carrying Tn5 induced mutations. Twenty auxotrophs chromosome DNA were hybridized with Tn5 DNA labeled with 32P respectively, all auxotrophs has positive reaction. Therefore, we concluded from genetic and physical data that auxotrophs resulted from Tn5 transposition from PJB4JI into C-3-1 chromosome.